Overview
A warm and very dry February for Illinois.
Temperatures averaged 34.9° in February, 3.8° above the 1991-2020 long-term average. The month was the 20th warmest February on record for Illinois.
Precipitation statewide in February was 0.52 inches, 1.59 inches below the 1991-2020 statewide long-term average. February 2026 was the 4th driest February on record in Illinois
Mean provisional streamflow data was sufficiently limited, due to winter conditions, to preclude estimating an aggregate mean streamflow condition statewide for February. Available hydrograph data suggests flow conditions were below normal to much below normal throughout central Illinois.
Water surface levels at the end of February were below the full pool or target level at 14 of 21 reporting reservoirs. At the end of February, Lake Shelbyville was 0.2 feet above the March 1 target level, Carlyle Lake level was 0.5 feet above the March 1 target level, and Rend Lake was 0.6 feet below the spillway level.
Lake Michigan’s mean level was below its long-term mean for the month.
Shallow groundwater levels were 3.68 feet below the long-term average at the end of February. Levels averaged 0.57 feet above December and 1.96 feet below last year.
Weather/Climate Information (Trent Ford)
The following description of temperatures, precipitation, severe weather, and drought comes from data compiled by networks that report to the National Oceanic and Atmospheric Administration (NOAA). These data are provisional and may change slightly over time.
February in Illinois was warmer and much drier than the 1991-2020 statewide normal.
Temperatures averaged 34.9°F statewide, 3.8° above the 1991-2020 normal for February, 5.7° above the 20th Century average, and 3.9° above the last 30-year average February temperature. Last month was the 20th warmest February on record in Illinois (Table 1a). February average temperatures ranged from the low 40s in southern Illinois to the high 20s in northern Illinois, between 1 and 7 degrees above the 1991-2020 normal (Figure 2). During the peak of extreme cold in early February, many stations across Illinois recorded nighttime low temperatures well below 0, including -8 degrees in Paris and -2 in Aurora. Meanwhile, the milder weather in mid-February brought some impressive daytime highs including 77 degrees in Cahokia Heights and 72 in Moline. The coldest place in the state last month was Stockton in Jo Daviess County with an average February temperature of 28.5 degrees, and the warmest place in the state was Crab Orchard in Williamson County with an average temperature of 41.5 degrees. The milder weather last month broke 76 daily high maximum temperature records and 31 daily high minimum temperature records. Meanwhile, the extreme cold in early February and the third week of the month broke 2 daily low maximum temperature records and 1 daily low minimum temperature record.
Precipitation statewide in February was 0.52 inches, 1.59 inches below the 1991-2020 statewide normal, 1.34 inches below the 20th Century average, and 1.67 inches below the last 30-year average for February. Last month was the 4th driest February on record in Illinois. Total February precipitation ranged from less than a quarter of an inch in much of northern Illinois to just over 3 inches in isolated parts of south-central Illinois. The state was 1 to 4 inches drier than normal last month (Figure 3).
Last month was the driest February on record in Moline (Trace), the second driest on record in Rockford (0.12”), the third driest on record in Chicago (0.16”), the third driest on record in Springfield (0.45”), the second driest on record in Champaign-Urbana (0.18”), the third driest on record in Carbondale (0.51”), and the second driest on record in Mt. Vernon (0.08”). Not only was last month the driest February on record in Moline, but it was the only month (of any calendar month) on record there to not record any measurable precipitation. Records in Moline go back to 1872, meaning February 2026 was the driest month in the Quad Cities in the last 154 years, or – put another way – the driest month since at least the Ulysses S. Grant administration.
Snow: February united the entire state with a substantial lack of snow. Total snowfall for the last month of meteorological winter ranged from virtually nothing in southern Illinois to just over 3 inches in parts of western Illinois. February snowfall deficits ranged from 1-2 inches less than average in southern Illinois to 8-10 inches less than normal along the Wisconsin border in northern Illinois.
Winter: Climatological winter runs from December through February and is the coldest season of the year in Illinois. Midwest winters have warmed at a much faster rate than the other three seasons over the past 100+ years because of human-caused climate change. Consequently, many of the past decade’s winter seasons have been very mild. However, the winter of 2025-26 began with some colder weather in December and much of January. February’s milder weather, though, brough the average winter temperature right to the 1991-2020 normal of 29.7 degrees (Table 1b). The past winter season’s average temperature was 1.7 degrees above the 20th Century average and 0.3 degrees below the last 30-year average. Overall, it was the 42nd warmest winter on record statewide.
Although December and January were not as extremely dry as February, they were not remarkably wet either. The statewide total meteorological winter precipitation in Illinois was 2.99 inches, which is 3.86 inches below the 1991-2020 normal, 3.32 inches below the 20th Century average, and 4.00 inches below the most recent 30-year average. The 2025-26 winter was the 4th driest on record in Illinois and was the driest since the winter of 1962-63.
Illinois Climate Network (ICN) (Jennie Atkins)
The Illinois Climate Network (ICN) consists of 20 stations across the state which collects hourly weather and soil information.
Winds were calmer in February, averaging 7.3 mph or 1.1 mph lower than January and 1.3 mph below the network’s long-term average. ICN Bondville (Champaign County) again had the windiest month with an average wind speed of 11.1 mph. The highest recorded wind gust was 45.5 mph at ICN Peoria (Tazewell County) on February 20.
Air temperatures averaged 35.3° for the month, 10.6° warmer than January and 4.3° above the long-term average. Station highs were in the 60s and 70s with lows down the negatives and single digits. The highest recorded temperature was 75.3°, measured at ICN Perry (Pike County) on February 27. The lowest was -4.0° at ICN Stelle (Ford County) on February 1.
Soil temperatures were 0.6° lower (8 inches under sod) to 2.8° higher (2 inches under bare soil) than January. Under bare soils, temperatures ranged from 19.0 to 67.3° at 2 inches and 18.0 to 60.5° at 4 inches. Temperatures under sod ranged from 21.6 to 57.0° at 4 inches and 26.9 to 54.5° at 8 inches.
The network was dry again in February. Precipitation average 0.64 inches, 1.55 inches below the long-term average. Sixteen out of 20 stations received less than 1 inch for the month and 11 of those received less than 0.5 inches. ICN St Charles (Kane County) had the lowest total, recording only 0.12 inches for the month or 1.54 inches below its long-term average. The highest total was 1.73 inches, measured at ICN Brownstown (Fayette County).
Soil moisture will return to the IWCS in Spring 2026.
Surface Water Information (Bill Saylor)
Provisional monthly mean flows for this month for 26 streamgaging stations located throughout Illinois are shown in Table 2, compared to statistics of past record of monthly mean flows at those stations for the same month. Both recent and long-term data are retrieved from USGS online data services following the end of the month. Years of record values in Table 2 represent the number of past monthly values included in the Table 2 statistics; at some stations, the available record may not be continuous. Additional source data may be available from USGS.
The statewide percent of historical mean flow and percent of historical median flow are calculated by dividing the sum of the average flows this month at stations in Table 2 by the sum of the historical mean and median flows calculated for the month, respectively, at the same stations. This method is intended to weight individual observations proportionately in the aggregate comparison. (The Illinois River and Rock River stations are excluded from the statewide calculation because other rivers listed in Table 2 contribute to their flow.)
In February, streamflow data was not available for extended periods at several gaging stations, due to winter conditions or equipment outages. By press time, USGS had estimated streamflow data at some but not all Table 2 stations where the automated record was incomplete. Sufficient data was not available to estimate an aggregate mean streamflow condition statewide for February. Available hydrograph data suggests flow conditions were below normal to much below normal throughout central Illinois. The monthly mean streamflow of the Sangamon River at Monticello was the lowest for the calendar month of February in the period of record of the station.
Water-Supply Lakes and Major Reservoirs. Table 3 lists selected reservoirs in Illinois, their normal pool or target water surface elevation, and data related to observed variations in water surface elevations. Reservoir levels are obtained from a network of cooperating reservoir operators who report water levels each month. Current reservoir levels reported in Table 3 are representative of the end of the reported month and are presented as the difference in feet from seasonal target level or from full pool, as applies. Years of record represent the number of past reports for the same month used to calculate the average of the month-end values presented in Table 3. For some reservoirs, this average does not include additional period of record prior to a substantial change in reservoir operation. Most reservoirs in Table 3 serve as public water supplies, with the exceptions noted in the last column.
Compared to end-of-January water levels at 21 reservoirs for which levels were reported last month and this month, reported end-of-February water levels were lower at 5 reservoirs, higher at 14 reservoirs, and about the same as at the end of January at 2 reservoirs. For the 21 reservoirs with measurements reported for the end of February, water levels were below normal target pool or spillway level at 14 reservoirs, above normal target pool or spillway level at 6 reservoirs, and at about the target level or spillway level at 1 reservoir.
Major Reservoirs. Compared to water levels at the end of January, at the end of February the water level at Lake Shelbyville was 0.1 foot higher, Carlyle Lake was 0.2 feet higher, and Rend Lake was 0.5 feet higher. At the end of February, Lake Shelbyville was 0.2 feet above the March 1 target level, Carlyle Lake level was 0.5 feet above the March 1 target level, and Rend Lake was 0.6 feet below the spillway level.
Great Lakes. Current month mean and end-of-month values are provisional and are relative to International Great Lakes Datum 1985. The February 2026 mean level for Lake Michigan was 577.5 feet. The monthly mean level one year ago (February 2025) was 577.8 feet. The long-term average lake level for February is 578.4 feet, based on 1918-2024 data. In this period of record, the lowest mean level for Lake Michigan for February occurred in 1964 at 576.1 feet, and the highest mean level for February occurred in 2020 at 581.5 feet. The month-end level of Lake Michigan was 577.5 feet. All values are provided by the U.S. Army Corps of Engineers Detroit District.
Groundwater Information (Jennie Atkins)
Despite the dry weather water tables increased in February, ending the month 0.57 feet higher than January on average.
Thirteen wells ended the month higher. The largest increase was at the Brownstown well (Fayette County) that was 3.61 feet higher on February 28. The increase was due to timing with the little precipitation at the well occurring in the middle and end of the month.
Other wells followed a similar pattern – significant increases in response to precipitation mid-month and water levels slowly declining through the end of the month. Nine wells reported increases of more than a foot for the month.
However, there were significant decreases in several wells. The largest decline was at the Fermi Lab well (DuPage County) that fell 1.64 feet. DuPage County was especially dry receiving 0.21 inches of precipitation or less in February.
Wells averaged 1.96 feet below February 2025, 3.53 feet below the 15-year average, and 3.68 feet below the long-term record (Table 4).
Data sources for the IWCS include the following:
CPC - Climate Prediction Center
ISWS - Illinois State Water Survey
MRCC - Midwestern Regional Climate Center
NCEI - National Centers for Environmental Information
NWS – National Weather Service
SPC – Storm Prediction Center
USACE – U.S. Army Corps of Engineers
USDM – US Drought Monitor
USGS – US Geological Survey
WARM – Water and Atmospheric Resources Monitoring Program